Variants of human papilloma virus antigens

ABSTRACT

Variants of human papilloma virus (HPV) E6 and E7 proteins able to elicit a humoral and/or cellular immune response against HPV in a host animal but not being cell-transforming in the host animal are disclosed, and are useful in treatment or prevention of diseases or conditions involving HPV.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No. 08/860165, dated Sep. 22, 1997, now U.S. Pat. No. 6,044,557 the contents of which are incorporated herein by reference. U.S. application Ser. No. 08/860165 corresponds to and is a 371 to International Patent Application No. PCT/AU95/100868(WO96/19496).

FIELD OF THE INVENTION

This invention relates generally to variants of human papilloma virus (HPV) antigens, and in particular it relates to non-transforming variants of HPV antigens which are suitable for use in vaccines. The invention also extends to vaccine compositions which include these variants of HPV antigens as active immunogens, as well as to methods of use of these variants to elicit an immune response against HPV.

BACKGROUND OF THE INVENTION

Papillomaviruses are small DNA viruses that infect a variety of animal species. Some are associated with the development of malignancies in their natural hosts. Over 60 types of human papillomavirus (HPV) have been identified. These infect humans at a variety of body locations and are responsible for common skin warts, laryngeal papillomas, genital warts and other wart-like lesions. Genital HPV infections are particularly common and a number of HPV types, but most frequently types 6, 11, 16 and 18, infect the genital tract in both men and women. In women, HPVs infect various portions of the genital tract including the cervix.

Genital HPVs are a significant clinical problem. HPV infection of the ano-genital region is now regarded as the most common form of viral sexually-transmitted disease (STD). The viruses cause genital infections which become manifest in one of three ways:

i clinical infection, where gross genital warts are visible;

ii subclinical infection, where viral lesions are not obvious but are detectable using special viewing techniques; and

iii latency, where the only sign of infection is the presence of HPV DNA.

Subclinical infections are common. It is estimated that 2 to 4% of Papanicolaou (Pap.) smears show evidence of HPV. Latent infections are even more frequent and the majority of adults harbour one or more types of genital HPV.

Carcinoma of the uterine cervix (CaCx) is a common cancer in women. Two forms of cervical cancer are recognised; squamous cell carcinoma (SCC) is by far the most frequent representing about 90% of observed cases; adenocarcinoma, a cancer of the secretion cells, accounts for about 10%. Cancer of the cervix develops through pre-cancerous intermediate stages to invasive forms (the carcinoma) which can become life threatening. The pre-cancerous stages of increasing severity are known as cervical intraepithelial neoplasia (CIN) grades 1 to 3. Over a 20 year period about 40% of the untreated CIN3 patients develop invasive cancer, the increasingly serious forms of which are known as stage I to IV. Invasive cancer frequently leads to death.

Cervical cancer in both its pre-cancerous and invasive stages is one of the few cancers for which a highly reliable and relatively cheap screening method is available. The Papanicolaou (Pap.) smear involves cytological examination of cervical scrapes to test for the presence of abnormal cervical cells which are indicative of pre- or invasive cancer. Detection of abnormalities leads to further investigation and treatment if necessary.

To be effective at reducing the number of cervical cancers and resultant deaths, Pap. smear screening is undertaken on a mass scale and ideally includes all women of sexually-actve age. Detection and subsequent treatment of CIN has a very high success rate in the prevention of invasive cancer, while early detection of the latter can have a marked effect on mortality.

Most developed countries have highly developed Pap. smear screening programs which have resulted in a 30% drop in age-specific mortality due to CaCx between 1960 and 1980. However, apart from the Scandinavian countries, few developed countries screen more than 50 to 60% of women, allowing CaCx and resultant deaths to remain a significant problem. In the developing world the situation is even worse as few organised screening programs exist, resulting in 400,000 new cases of invasive cancer annually in these countries.

As outlined earlier, a variety of types of HPV cause genital infections in humans, although four types (6, 11, 16, 18) predominate. Evidence collected over the past 15 years strongly suggests that several of the HPVs are associated with the development of cervical cancer. Indeed many researchers have concluded that specific HPV types are the essential aetiologic factor responsible for the development of many of the cancers.

Infection with HPV-16 and HPV-18 has been associated with the development of cancer of the cervix. It has been postulated that HPV acts as an initiator in cervical carcinogenesis and that malignant transformation depends on interaction with other factors. Infections with HPV-6 and HPV-11 have been associated with the development of genital warts. The incidence of HPV infection appears to be increasing as shown by a large increase recently in patient visits related to genital HPV infections in both males and females and the presence of HPV in Pap. smears of some women under 30 years of age.

The nature of HPV-16 in particular and papilloma viruses in general has been well studied recently. HPV-16 contains a 7904 bp double-stranded DNA genome (Siedorf, K. et aL, Virology (1985) 145:181-185). The capsid is 50 nm and contains 72 capsomers (Klug, A., J. Mol. Biol. (1965) 11:403-423). U.S. Pat. No. 4,777,239 discloses a series of 17 synthetic peptides which are said to be capable of raising antibodies to HPV-16 and thus may be useful for diagnostic purposes. In addition, European Patent 0 412 762 discloses polypeptides which are antagonists of the biochemical interaction of the HPV E7 protein and the retinoblastoma gene (RBG) protein, and which are said to be useful in the treatment of genital warts and cervical cancer.

The DNAs of several papilloma viruses have been sequenced, including several HPV types, bovine papillomavirus (BPV) and cottontail rabbit papillomavirus (CRPV). All of these display similar patterns of nucleotide sequence with respect to open reading frames. The open reading frames can be functionally divided into early regions (E) and late regions (L); the E regions are postulated to encode proteins needed for replication and transformation; and the L regions to encode the viral capsid proteins (Danos, O., et al., J. Invest. Derm. (1984) 83:7s-11s).

Two HPV encoded proteins, E6 and E7, are thought to be involved in the pathogenesis of HPV-induced abnormal cell proliferation (reviewed in Stoppler et al., Intervirology, (1994) 37:168-179). The amino acid sequences of the HPV-16 E6 and E7 proteins as deduced from the nucleic acid sequence are shown in Siedorf et al., Virology, (1985) 145:181-185.

The HPV genes encoding the E6 and E7 proteins are invariably expressed in tissue or tumor cells obtained from cervical cancers associated with HPV infection. In addition, the HPV E6 and E7 genes derived from the HPV-16 strain are capable of inducing epithelial cell transformation in cell culture without the presence of other HPV genes. These observations indicate that at least part of the stimulation of cell proliferation caused by HPV infection is due to the E6 and E7 viral proteins.

The HPV E6 and E7 proteins are believed to be effective immunological targets for tumour regression. As described above, however, the E6 and E7 genes are known to “transform” cells possibly by the action of their protein products in interfering with cellular proteins involved in the control cell growth. Accordingly, if even minute traces of DNA encoding the E6 and E7 proteins were to be present in a vaccine preparation, this could cause that vaccine preparation to initiate irreversible transformation events in the cells of a recipient of the vaccine preparation. It is an object of the present invention to provide non-transforming variants of the HPV E6 and E7 proteins which are able to induce in a host animal (particularly a human) a range of humoral and cellular immune responses, and which are therefore suitable for use in the production of vaccines for the prevention, prophylaxis, therapy and treatment of HPV-induced diseases or other conditions which would benefit from inhibition of HPV infection.

In the work leading to the present invention, it has been recognised that there are four ways to induce immune responses to E6 and/or E7 proteins:

(i) use whole proteins (this introduces the possibility that contaminating DNA may be associated with the proteins);

(ii) use point mutants (this can lead to reversion to native protein, which requires multiple mutations to avoid; in addition, any point mutation leads to loss of potentially vital epitopes);

(iii) use specific peptides (this requires a very large number of peptides, the identification of which is very complex, to make a vaccine of broad utility); and

(iv) use variants such as fusions and combinations of deletion mutants (this method has none of the above limitations).

In addition to the cell transforming properties of the E7 protein itself, fusions of this protein with β-galactosidase have also been shown to be cell-transforming (Fujikawa et al., Virology, 204, 789-793, 1994). Accordingly, it could not be predicted that fusions of E6 and/or E7 moieties, either full length or non-full length, would not also be cell-transforming.

SUMMARY OF THE INVENTION

In one aspect the present invention provides as an isolated protein, a variant of the HPV E6 or E7 protein which variant is able to elicit a humoral and/or cellular immune response against HPV in a host animal but which is not cell-transforming in the host animal.

In another aspect, the present invention provides a method for eliciting an immune response against HPV in a host animal, which method comprises administering to the host animal an effective amount of a variant of the HPV E6 or E7 protein which variant is able to elicit a humoral and/or cellular immune response against HPV in a host animal but which is not cell-transforming in the host animal.

In yet another aspect, the present invention provides a vaccine composition for use in eliciting an immune response against HPV in a host animal, which comprises a variant of the HPV E6 or E7 protein which variant is able to elicit a humoral and/or immune response against HPV in a host animal but which is not cell-transforming in the host animal, and optionally an adjuvant, together with a pharmaceutically acceptable carrier and/or diluent.

The invention also extends to the use of a variant of the HPV E6 or E7 protein which variant is able to elicit a humoral and/or cellular immune response against HPV in a host animal but which is not cell-transforming in the host animal, and optionally an adjuvant, in eliciting an immune response against HPV in a host animal.

Throughout this specification, unless the context requires otherwise, the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(a)-(d) show domain maps for the different proteins referenced herein.

FIG. 2 shows amounts of fusion protein produced in transformed cells following IPTG induction in Example 1.

FIG. 3 shows a Western blot of a protein described in Example 2.

FIG. 4(a) shows a Coomassie stained gel indicating amounts of fusion protein produced in transformed cells following IPTG induction in Example 3(i).

FIG. 4(b) is a Western blot confirming the identity of the protein of Example 3(i).

FIG. 5(a) shows a Coomassie stained gel indicating amounts of fusion protein produced in transformed cells following IPTG induction in Example 3(ii).

FIG. 5(b) is a Western blot confirming the identity of the protein of Example 3(ii).

FIGS. 6(a) and (b) show coomassie stained gel and Western blot, respectively, confirming purity and identity of the product of Example 5.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, references to the variant of this invention as being “not cell-transforming in the host animal” mean that the cell-transforming property of the “parent” or wild-type HPV E6 or E7 protein has been reduced, and preferably effectively eliminated, in the variant. In particular, these references indicate that this cell-transforming property has been significantly reduced in comparison with wild-type E6 or E7 protein in appropriate test systems.

It will be appreciated that where the non-transforming variant HPV E6 or E7 protein of this invention is produced by expression of an appropriate encoding recombinant DNA molecule, the nature of that encoding DNA, unlike the wild-type E6 or E7 genes, would not have the potential to initiate irreversible transformation events in the cells of the host animal.

The variant HPV E6 or E7 proteins of the present invention include, but are not limited to, deletion mutants of the wild-type E6 or E7 proteins in the form of non-full length fragments of the wild-type proteins, as well as fusion proteins in which E6 and/or E7 moieties are fused, optionally with a linkage of from 1 to 50, preferably a short linkage of from 1 to 20, and more preferably from 1 to 5, amino acid residues between the E6 and/or E7 moieties. The E6 and/or E7 moieties in such a fusion protein may comprise the full wild-type E6 or E7 proteins, or alternatively they may comprise non-full length fragments of the wild-type proteins. The fusion proteins may also comprise other moieties fused or otherwise coupled thereto, for example moieties to assist in purification of the fusion protein (for example, a glutathione-S-transferase or GST moiety or hexa-His moiety) or to enhance the immunogenicity of the fusion protein (for example an adjuvant such as diphtheria or cholera toxin or a non-toxic derivative thereof such as the holotoxoid or B sub-unit of cholera toxin).

The term “non-full length fragment” is used herein to describe polypeptides which may for example comprise deletion mutants of the E6 or E7 proteins corresponding to at least 50%, more preferably 60-70%, and even 80-90% of the full-length E6 or E7 protein sequence. By way of example only, the fragments may be deletion mutants corresponding to the N-terminal or C-terminal two-thirds of the E6 or E7 proteins.

Suitable non-full length fragments, and fusion proteins which comprise the E6 and/or E7 proteins or non-full length fragments thereof, as described above may be readily produced by techniques which are well known in the art and which are described by way of example below. It will be appreciated by persons skilled in this art that variant HPV E6 or E7 proteins as described above including fusion proteins which comprise various combinations of the E6 and/or E7 moieties may be readily produced using these known techniques, and then tested using routine methods to establish whether the resultant fusion protein or other variant protein meets the criteria of the present invention, that is whether it is able to elicit a humoral and/or cellular immune response in a host animal but is not cell-transforming in the host animal.

Preferably, the host animal is a human, however the host animal may also be a non-human mammal.

The present invention is particularly, but not exclusively, directed to variants of the E6 or E7 proteins of the HPV-16 and HPV-18 genotypes, however it will be appreciated that the invention extends to variants of the corresponding proteins in other HPV genotypes, particularly the HPV-6 and HPV-11 genotypes which are causative agents of condylomata acuminta, and other genotypes which have oncogenic potential of a type similar to HPV-16 and HPV-18.

Previous work in this area has shown that vaccination of rats with live viral vectors expressing HPV E6 or E7 proteins leads to rejection of transplanted E7-bearing tumour cells (Meneguzzi et al., Virology, 181:62-69, 1991), while vaccination of cattle with an adjuvanted HPV E7 vaccine leads to accelerated rejection of tumours induced by bovine papillomavirus (Campo, Cancer Cells, 3:421-426, 1991).

The variant HPV E6 or E7 proteins of the present invention are provided as isolated proteins, that is they are substantially free of other HPV proteins, and find particular utility for the treatment of genital warts, cervical cancer or other conditions caused by HPV in man. The variant proteins can be included in pharmaceutical compositions for the treatment or prevention of diseases involving HPV as well as the other conditions discussed above.

The variant HPV E6 or E7 proteins of the invention may be used to raise antibodies and/or induce cellular immune responses, either in subjects for which protection against infection by HPV is desired, i.e. as prophylactic vaccines, or to heighten the immune response to an HPV infection already present, i.e. as therapeutic vaccines. They also can be injected into production species to obtain antisera. In lieu of the polyclonal antisera obtained in the production species, monoclonal antibodies may be produced using the standard methods or by more recent modifications thereof by immortalising spleen or other antibody-producing cells for injection into animals to obtain antibody-producing clones. The polyclonal or monoclonal antibodies obtained, corrected if necessary for species variations, can also be used as therapeutic agents.

Direct administration of the variant proteins to a host can confer either protective immunity against HPV or, if the subject is already infected, a boost to the subject's own immune response to more effectively combat the progress of the HPV induced disease.

The magnitude of the prophylactic or therapeutic dose of a variant HPV E6 or E7 protein of this invention will, of course, vary with the group of patients (age, sex, etc.), the nature or the severity of the condition to be treated and with the particular variant protein and its route of administration. In general, the weekly dose range for use lies within the range of from about 0.1 to about 5 μg per kg body weight of a mammal.

Any suitable route of administration may be employed for providing a mammal, especially a human, with an effective dosage of a variant protein of this invention. For example, oral, rectal, vaginal, topical, parenteral, ocular, nasal, sublingual, buccal, intravenous and the like may be employed. Dosage forms include tablets, troches, dispersions, suspensions, solutions, capsules, creams, ointments, suppositories, aerosols and the like. Said dosage forms also include injected or implanted slow releasing devices specifically designed for this purpose or other forms of implants modified to additionally act in this fashion.

If the variant proteins are to be administered as vaccines, they are formulated according to conventional methods for such administration to the subject to be protected. If the antibodies are to be used for therapeutic purposes, it is generally desirable to confer species characteristics upon them compatible with the subject to be treated. Accordingly, it is often desirable to prepare these antibodies in monoclonal form since fusion with suitable partners is capable of conferring the desired characteristics on the secreted monoclonals.

The variant proteins may be delivered in accordance with this invention in ISCOMS™ (immune stimulating complexes), liposomes or encapsulated in compounds such as acrylates or poly(DL-lactide-co-glycoside) to form microspheres. The variant proteins may also be incorporated into oily emulsions and delivered orally.

Other adjuvants, as well as conventional pharmaceutically acceptable carriers, excipients, buffers or diluents, may also be included in the vaccine compositions of this invention. Generally, a vaccine composition in accordance with the present invention will comprise an immunologically effective amount of the variant HPV E6 or E7 protein, and optionally an adjuvant, in conjunction with one or more conventional pharmaceutically acceptable carriers and/or diluents. An extensive though not exhaustive list of adjuvants can be found in Coulter and Cox, “Advances in Adjuvant Technology and Application”, in Animal Parasite Control Utilizing Biotechnology, Chapter 4, Ed. Young, W. K., CRC Press, 1992. As used herein “pharmaceutically acceptable carriers and/or diluents” include any and all solvents, dispersion media, aqueous solutions, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents and the like. The use of such media and agents for pharmaceutical active substances is well known in the art and is described by way of example in Remington's Pharmaceutical Sciences, 18th Edition, Mack Publishing Company, Pennsylvania, U.S.A.

In practical use, a variant protein of this invention can be combined as the active ingredient in intimate admixture with a pharmaceutical carrier according to conventional pharmaceutical compounding techniques. The carrier may take a wide variety of forms depending on the form of preparation desired for administration, e.g. oral or parenteral (including intravenous and intra-arterial). In preparing the compositions for oral dosage form, any of the usual pharmaceutical media may be employed, such as, for example, water glycols, oils, alcohols, flavouring agents, preservatives, colouring agents and the like in the case of oral liquid preparations, such as, for example, suspensions, elixirs and solutions; or carriers such as starches, sugars, microcrystalline cellulose, diluents, granulating agents, lubricants, binders, disintegrating agents and the like in the case of oral solid preparations such as, for example, powders, capsules and tablets. Because of their ease of administration, tablets and capsules represent the most advantageous oral dosage unit form, in which case solid pharmaceutical carriers are obviously employed. If desired, tablets may be sugar-coated or enteric-coated by standard techniques.

In addition to the common dosage forms set out above, the variant proteins of this invention may also be administered by controlled release means and/or delivery devices, including by way of example, the controlled release preparations disclosed in International Patent Specification No. PCT/AU93/00677(Publication No. WO 94/15636).

Pharmaceutical compositions of the present invention suitable for oral or parenteral administration may be presented as discrete units such as capsules, cachets or tablets each containing a predetermined amount of the active ingredient, as a powder or granules or as a solution or a suspension in an aqueous liquid, a non-aqueous liquid, an oil-in-water emulsion or a water-in-oil liquid emulsion. Such compositions may be prepared by any of the methods of pharmacy but all methods include the step of bringing into association the active ingredient with the carrier which constitutes one or more necessary ingredients. In general, the compositions are prepared by uniformly and intimately admixing the active ingredient with liquid carriers or finely divided solid carriers or both, and then, if necessary, shaping the product into the desired presentation.

Further features of the present invention are more fully described in the following Example(s). It is to be understood, however, that this detailed description is included solely for the purposes of exemplifying the present invention, and should not be understood in any way as a restriction on the broad description of the invention as set out above.

EXAMPLE 1

Cloning and Expression of GST E6/E7 Fusion Protein.

A molecule consisting of HPV-16 E6 and E7 sequences as an “in-frame” fusion was created as follows. A clone of HPV-16 DNA containing both E6 and E7 genomic sequences served as the template for separate PCR amplification of E6 and E7 using oligonucleotides:

(a) (5′)CGCTCGAGAGATCTCATATGCACCAAAAGAGAACTGC(3′) (SEQ ID NO:1) and

(b) (5′)CGCCCGGGCAGCTGGGTTTCTCTACGTG(3′) (SEQ ID NO:2) for E6; and

(c) (5′)CGCCCGGGATGCATGGAGATACACCTACATTGCATG(3′) (SEQ ID NO:3) and

(d) (5′)CGGTCGACGGATCCTGGTTTCTGAGAACAGATGGG(3′) (SEQ ID NO:4) for E7.

A SmaI recognition site at the 3′ end of E6 and the 5′ end of E7 facilitated the fusion and introduced two additional amino acids (proline and glycine) between E6 and E7. Additional restriction enzyme recognition sites at the 5′ and 3′ boundaries of the fusion molecule (introduced in the oligonucleotides) aided in subsequent cloning procedures.

The fused E6/E7 sequence was cloned as a Bg/II-BamH1 fragment into vector pDS56 (Stuber et al., EMBO J., (1984) 3:3143-3148) which provided an in-frame 3′ hexa-his(hh) sequence. From this, E6/E7hh was removed as a EcoRI/Hind III fragment and subcloned into pGEM 7+3, which was created by inserting the BamH1/HindIII portion of the pGEM3-Zf(+)(Promega) polylinker into the BamH1/HindIII site of the multiple cloning site of the pGEM7-Zf(+)(Promega) vector. E6/E7hh was then removed from pGEM7+3 as a EcoRI/Sal I fragment and inserted into the multiple cloning site of pGEX-4T-1(Pharmacia) to produce pGEX-4T-1 E6/E7hh. This plasmid was used to transform a variety of E. coli strains including TOPP2 (Stratagene) and BL21 (Amrad/Pharmacia). Both types of transformed cells produced a significant amount of fusion protein following IPTG induction (FIG. 2). The fusion protein (GST E6/E7hh represented schematically in FIG. 1awas in the expected size range of around 60 kDa. The identity of the protein was confirmed by Western blots probed with two monoclonal antibodies directed against E7 (LHIL.16E7.8F and LHIL.16E7.6D, Tindle at al. Journal of General Virology, (1990) 71:1347-1354) (FIG. 3).

EXAMPLE 2

Cloning and Expression of E6/E7 Fusion Protein

In order to express E6/E7hh as protein lacking GST, a termination codon was introduced into pGEX-4T-1 E6/E7hh at a unique BalI site 3′ to, and in-frame with, the GST translation initiation codon using the phosphorylated linker TGCTCTAGAGCA (SEQ ID NO: 15). After transforming E. coli strain BL21 with this new plasmid ([GST] E6/E7hh) a significant amount of protein (E6/E7hh, represented schematically in FIG. 1b) was produced following IPTG induction at a size of approximately 33 kD which corresponds to the size expected of a E6/E7hh fusion protein (FIG. 2). Identity of this protein was confirmed by Western blot using the same monoclonal antibodies as in Example 1 (FIG. 3).

EXAMPLE 3

Cloning and Expression of Deleted (non-full length) Forms of E6 and E7

(i) Construction of ΔE6C/ΔE7N

Full length E6/E7 in pGEM3(Promega) served as a template for PCR amplification of deleted forms of E6/E7 using oligonucleotides

5′GCGCGAATTCTATTAAGGAGCCCGGGATGGGGAATCCATATGCTGTAT3′ (SEQ ID NO:5) and

5′CGCGAGATCTCCGAAGCGTAGAGTCACACTTG3′ (SEQ ID NO:6).

The resulting truncation of E6/E7 lacking sequences (189 bp) at the N terminal of E6 and C terminal of E7 (96 bp) was subcloned into pGEX-4T-1 containing a termination codon in the GST sequence to produce [GST] ΔE6C/ΔE7Nhh. This plasmid was used to transform E. coli strain BL21. Transformed cells expressed a significant amount of fusion protein (ΔE6C/ΔE7Nhh, represented schematically in FIG. 1c) following IPTG induction (FIG. 4a) producing a protein of the approximate expected size (20 kD). The identity of this protein was confirmed by Western blot using the same monoclonal antibodies as in Example 1 (FIG. 4b).

(ii) Construction of ΔE7C/ΔE6N

Using oligonucleotides (a) in Example 1 and 5′CGCCCGGGTAATGTTGTTCCATACAAACTA3′ (SEQ ID NO:7) an N-terminal representation of E6 comprising 285 bp was amplified from the same HPV-16 clone utilised in Example 1. As well, oligonucleotides 5′CGCCCGGGGAGGAGGAGGATGAAATAGATG3′ (SEQ ID NO: 8) and (d) in Example 1 were used to produce a 198 bp C-terminal E7 sequence. These were each blunt cloned into pGEM7-Zf(+) (Promega). A fusion cassette was formed by restricting the E6 clone with KpnI/Bg/II and inserting the E7 sequence upstream as a Kpnl/BamHI fragment. This fused sequence was then reamplified with SmaI and Bg/II cloning sites for insertion into pGEX-4T-1 containing a termination codon in the GST sequence to produce [GST] ΔE7C/ΔE6Nhh. After transformation into E. coli BL21, protein production was assayed by PAGE followed by Coomassie staining and Western blotting (FIGS. 5a and 5 b). A protein (ΔE7C/ΔE6Nhh, represented schematically in FIG. 1d) of the expected size (20 kD) was evident on Western blots.

EXAMPLE 4

DNA Sequencing of E6/E7 Full Length and Deletion Constructs

E6/E7 constructs were sequenced in both directions by the dideoxy method using primers that generated overlapping sequence information. The ^(T7)Sequencing™ Kit (Pharmacia) was used to generate ³⁵S-labelled chain-terminated fragments which were analysed on a Sequi-Gen™ (Biorad) electrophoretic gel apparatus. The DNA and corresponding amino acid sequences for E6/E7hh (PPV162.DNA), ΔE6C/ΔE7Nhh (CAD600.SEQ) and ΔE7C/ΔE6Nhh (C620.TXT) are set out below (SEQ ID NO: 9 and SEQ ID NO: 10; SEQ ID NO: 11 and SEQ ID NO: 12; SEQ ID NO: 13 and SEQ ID NO: 14; respectively).

File: PPV162.DNA Range: 1-801 Mode: Normal Codon Table: Universal 5′ ATG CAC CAA AAG AGA ACT GCA ATG TTT CAG GAC CCA CAG GAG CGA CCC AGA AAG --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Met His Gln Lys Arg Thr Ala Met Phe Gln Asp Pro Gln Glu Arg Pro Arg Lys TTA CCA CAG TTA TGC ACA GAG CTG CAA ACA ACT ATA CAT GAT ATA ATA TTA GAA --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Leu Pro Gln Leu Cys Thr Glu Leu Gln Thr Thr Ile His Asp Ile Ile Leu Glu TGT GTG TAC TGC AAG CAA CAG TTA CTG CGA CGT GAG GTA TAT GAC TTT GCT TTT --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Cys Val Tyr Cys Lys Gln Gln Leu Leu Arg Arg Glu Val Tyr Asp Phe Ala Phe CGG GAT TTA TGC ATA GTA TAT AGA GAT GGG AAT CCA TAT GCT GTA TGT GAT AAA --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Arg Asp Leu Cys Ile Val Tyr Arg Asp Gly Asn Pro Tyr Ala Val Cys Asp Lys TGT TTA AAG TTT TAT TCT AAA ATT AGT GAG TAT AGA CAT TAT TGT TAT AGT TTG --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Cys Leu Lys Phe Tyr Ser Lys Ile Ser Glu Tyr Arg His Tyr Cys Tyr Ser Leu TAT GGA ACA ACA TTA GAA CAG CAA TAC AAC AAA CCG TTG TGT GAT TTG TTA ATT --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Tyr Gly Thr Thr Leu Glu Gln Gln Tyr Asn Lys Pro Leu Cys Asp Leu Leu Ile AGG TGT ATT AAC TGT CAA AAG CCA CTG TGT CCT GAA GAA AAG CAA AGA CAT CTG --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Arg Cys Ile Asn Cys Gln Lys Pro Leu Cys Pro Glu Glu Lys Gln Arg His Leu GAC AAA AAG CAA AGA TTC CAT AAT ATA AGG GGT CGG TGG ACC GGT CGA TGT ATG --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Asp Lys Lys Gln Arg Phe His Asn Ile Arg Gly Arg Trp Thr Gly Arg Cys Met TCT TGT TGC AGA TCA TCA AGA ACA CGT AGA GAA ACC CAG CTG CCC GGG ATG CAT --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Ser Cys Cys Arg Ser Ser Arg Thr Arg Arg Glu Thr Gln Leu Pro Gly Met His GGA GAT ACA CCT ACA TTG CAT GAA TAT ATG TTA GAT TTG CAA CCA GAG ACA ACT --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Gly Asp Thr Pro Thr Leu His Glu Tyr Met Leu Asp Leu Gln Pro Glu Thr Thr GAT CTC TAC TGT TAT GAG CAA TTA AAT GAC AGC TCA GAG GAG GAG GAT GAA ATA --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Asp Leu Tyr Cys Tyr Glu Gln Leu Asn Asp Ser Ser Glu Glu Glu Asp Glu Ile GAT GGT CCA GCT GGA CAA GCA GAA CCG GAC AGA GCC CAT TAC AAT ATT GTA ACC --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Asp Gly Pro Ala Gly Gln Ala Glu Pro Asp Arg Ala His Tyr Asn Ile Val Thr TTT TGT TGC AAG TGT GAC TCT ACG CTT CGG TTG TGC GTA CAA AGC ACA CAC GTA --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Phe Cys Cys Lys Cys Asp Ser Thr Leu Arg Leu Cys Val Gln Ser Thr His Val GAC ATT CGT ACT TTG GAA GAC CTG TTA ATG GGC ACA CTA GGA ATT GTG TGC CCC --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Asp Ile Arg Thr Leu Glu Asp Leu Leu Met Gly Thr Leu Gly Ile Val Cys Pro ATC TGT TCT CAG AAA CCA AGA TCT CAT CAC CAT CAC CAT CAC TAA 3′ --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Ile Cys Ser Gln Lys Pro Arg Ser His His His His His His *** File: CAD600.SEQ Range: 1-519 Mode: Normal Codon Table: Universal                                                     54 5′ ATG GGG AAT CCA TAT GCT GTA TGT GAT AAA TGT TTA AAG TTT TAT TCT AAA ATT --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Met Gly Asn Pro Tyr Ala Val Cys Asp Lys Cys Leu Lys Phe Tyr Ser Lys Ile AGT GAG TAT AGA CAT TAT TGT TAT AGT TTG TAT GGA ACA ACA TTA GAA CAG CAA --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Ser Glu Tyr Arg His Tyr Cys Tyr Ser Leu Tyr Gly Thr Thr Leu Glu Gln Gln TAC AAC AAA CCG TTG TGT GAT TTG TTA ATT AGG TGT ATT AAC TGT CAA AAG CCA --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Ile Asn Cys Gln Lys Pro Tyr Asn Lys Pro Leu Cys Asp Leu Leu Ile Arg Cys CTG TGT CCT GAA GAA AAG CAA AGA CAT CTG GAC AAA AAG CAA AGA TTC CAT AAT --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Leu Cys Pro Glu Glu Lys Gln Arg His Leu Asp Lys Lys Gln Arg Phe His Asn ATA AGG GGT CGG TGG ACC GGT CGA TGT ATG TCT TGT TGC AGA TCA TCA AGA ACA --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Ile Arg Gly Arg Trp Thr Gly Arg Cys Met Ser Cys Cys Arg Ser Ser Arg Thr CGT AGA GAA ACC CAG CTG CCC GGG ATG CAT GGA GAT ACA CCT ACA TTG CAT GAA --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Arg Arg Glu Thr Gln Leu Pro Gly Met His Gly Asp Thr Pro Thr Leu His Glu TAT ATG TTA GAT TTG CAA CCA GAG ACA ACT GAT CTC TAC TGT TAT GAG CAA TTA --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Tyr Met Leu Asp Leu Gln Pro Glu Thr Thr Asp Leu Tyr Cys Tyr Glu Gln Leu AAT GAC AGC TCA GAG GAG GAG GAT GAA ATA GAT GGT CCA GCT GGA CAA GCA GAA --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Asn Asp Ser Ser Glu Glu Glu Asp Glu Ile Asp Gly Pro Ala Gly Gln Ala Glu CCG GAC AGA GCC CAT TAC AAT ATT GTA ACC TTT TGT TGC AAG TGT GAC TCT ACG --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Pro Asp Arg Ala His Tyr Asn Ile Val Thr Phe Cys Cys Lys Cys Asp Ser Thr CTT CGG AGA TCT CAT CAC CAT CAC CAT CAC TAA 3′ --- --- --- --- --- --- --- --- --- --- --- Leu Arg Arg Ser His Hjs His His His His *** File: C620.TXT Range: 1-519 Mode: Normal Codon Table: Universal 5′ ATG GAG GAG GAT GAA ATA GAT GGT CCA GCT GGA CAA GCA GAA CCG GAC AGA GCC --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Met Glu Glu Asp Glu Ile Asp Gly Pro Ala Gly Gln Ala Glu Pro Asp Arg Ala CAT TAC AAT ATT GTA ACC TTT TGT TGC AAG TGT GAC TCT ACG CTT CGG TTG TGC --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- His Tyr Asn Ile Val Thr Phe Cys Cys Lys Cys Asp Ser Thr Leu Arg Leu Cys GTA CAA AGC ACA CAC GTA GAC ATT CGT ACT TTG GAA GAC CTG TTA ATG GGC ACA --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Val Gln Ser Thr His Val Asp Ile Arg Thr Leu Glu Asp Leu Leu Met Gly Thr CTA GGA ATT GTG TGC CCC ATC TGT TCT CAG AAA CCA GGA TCT CAT ATG CAC CAA --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Leu Gly Ile Val Cys Pro Ile Cys Ser Gln Lys Pro Gly Ser His Met His Gln AAG AGA ACT GCA ATG TTT CAG GAC CCA CAG GAG CGA CCC AGA AAG TTA CCA CAG --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Lys Arg Thr Ala Met Phe Gln Asp Pro Gln Glu Arg Pro Arg Lys Leu Pro Gln TTA TGC ACA GAG CTG CAA ACA ACT ATA CAT GAT ATA ATA TTA GAA TGT GTG TAC --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Leu Cys Thr Glu Leu Gln Thr Thr Ile His Asp Ile Ile Leu Glu Cys Val Tyr TGC AAG CAA CAG TTA CTG CGA CGT GAG GTA TAT GAC TTT GCT TTT CGG GAT TTA --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Cys Lys Gln Gln Leu Leu Arg Arg Glu Val Tyr Asp Phe Ala Phe Arg Asp Leu TGC ATA GTA TAT AGA GAT GGG AAT CCA TAT GCT GTA TGT GAT AAA TGT TTA AAG --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Cys Ile Val Tyr Arg Asp Gly Asn Pro Tyr Ala Val Cys Asp Lys Cys Leu Lys TTT TAT TCT AAA ATT AGT GAG TAT AGA CAT TAT TGT TAT AGT TTG TAT GGA ACA --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- Phe Tyr Ser Lys Ile Ser Glu Tyr Arg His Tyr Cys Tyr Ser Leu Tyr Gly Thr ACA TTA AGA TCT CAT CAC CAT CAC CAT CAC TAA 3′ --- --- --- --- --- --- --- --- --- --- --- Thr Leu Arg Ser His His His His His His ***

EXAMPLE 5

Immunogenicity of E6/E7hh Protein

A. Purification of E6/E7hh

E. coli cells (strain BL21) containing the [GST] E6/E7hh plasmid were induced using 0.1-0.5 mM IPTG and harvested 3-4 hours after induction. The cells were pelleted by low speed centrifugation and inclusion bodies containing the E6/E7hh protein isolated by sonication and centrifugation. The inclusion pellet was solubilised in 7M Urea or 6M Guanidine HCl and subjected to nickel chelate column chromatography (Porath et.al., Biochemistry 22, 1621-1630, 1983). Protein was eluted using either an increasing gradient of imidazole or a decreasing pH gradient, and fractions containing E6/E7hh pooled and dialysed against 25 mM Tris, 0.5M NaCl, 1% NOG, 10 mM DTT pH7.5. The identity and purity of the dialysed product was determined by Coomassie stained polyacrylamide gel electrophoresis and Western blot using the monoclonal antibodies referred to in Example 1 (FIGS. 6a and 6 b).

B. Immunogenicity of E6/E7hh.

On day 0, two groups of 5 C57BL/6 mice (8 weeks old, female) were inoculated subcutaneously at the base of the tail with 0.1 mL of a formulation containing 6 μg ISCOMATRIX™, 19 μg E6/E7hh (purified as in A. above) in PBS pH7.2. A second dose of the formulation was administered at day 14 to group 1, and at day 17 to group 2. At day 21 and 24, mice in groups 1 and 2 (respectively) were bled. Serum antibody responses to E6/E7hh were then measured using the following solid phase EIA:

Nunc MaxiSorp EIA plates were coated with E6/E7hh by incubating 0.1 mL/well for 2 hours at 37° of a 10 μg/mL solution in 4M urea in 50 mM carbonate buffer, pH 9.5. The liquid was removed, and the plates were further incubated at 37° for 1 hour with 0.2 mL/well of 1 mg/mL casein in PBS pH 7.2. After 6 washes, 0.1 mL/well of test serum (diluted in PBS pH 7.2, 1 mg/mL casein, 0.5% Tween 20, 0.002% alphazurine A) was added, and the plates incubated for 1 hour at 37°. The plates were then again washed 6× with PBS pH 7.2, 0.5% Tween 20. To detect bound antibody, 0.1 mL of 0.1 μg/.ml KPL horseradish peroxidase-labelled goat anti-mouse IgG+IgM (H and L chain specific) in PBS pH 7.2, 1 mg/mL casein, 0.5% Tween 20, 0.002% alphazurine A was added to each well. The plates were incubated for 1 hour at 20°, washed 6× with PBS pH 7.2, 0.5% v/v Tween 20, then 0.1 mL of enzyme substrate (3,3′, 5,5′tetramethylbenzidine/H₂O₂ formulation, purchased from KPL) was then added. After 10 minutes incubation at 20°, the reaction was stopped by addition of 50 μl of 0.5M H₂SO₄. The coloured product was then measured at 450 nm in a vertical beam spectrophotometer. Titres were expressed as the reciprocal of the serum dilution resulting in an optical density value of 0.1.

Table 1 shows that all mice of both groups 1 and 2 produced a significant response following immunization. Titres ranged from 3.17 to 5.66 (expressed in the log₁₀ of the reciprocal dilution resulting in the optical density of 0.1 in the solid phase EIA described above). Pre-existing antibody levels were low or undetectable (measured in sera obtained on day 0 immediately prior to inoculation).

Clearly, the E6/E7hh fusion protein is highly immunogenic when administered to mice by this procedure.

As well, E6/E7hh was found to produce specific delayed-type hypersensitivity (DTH) following one dose of a formulation containing E6/E7hh plus ISCOM™ adjuvant. The mice produced specific DTH responses to both E6 and E7 when challenged in the ear with small doses of purified GST-E6 or GST-E7 proteins.

TABLE 1 Log dilution to 0.1 OD. Group/mouse 1/1 1/2 1/3 1/4 1/5 2/1 2/2 2/3 2/4 2/5 pre-bleed <2 <2 <2 <2 <2 <2 2.06 <2 <2 <2 final bleed 3.66 5.66 3.23 3.19 3.79 4.19 4.21 3.71 5.55 3.17

EXAMPLE 6

Transformation Studies of E6/E7 Gene Construct

An E6/E7 fusion DNA construct was subcloned into the multiple cloning site of plasmid vector pJ4Ω (Wilkinson et al, J. Exp. Med. (1988) 167:1442-58) as a BamHI fragment to produce pJ4ΩE6/E7. For comparison purposes pJ4Ω vectors containing HPV16 E6 (pJ4ΩE6) and HPV16 E7 (pJ4ΩE7) ORFs were used. Where neomycin selection was required, the pcDNA3 vector (Invitrogen) containing a neomycin resistance marker was utilised. These plasmids were amplified in E coli and plasmid DNA extracted by alkaline lysis and purified on resin (Qiagen) eluted, ethanol precipitated and resuspended in H₂O. DNA quantity and purity was determined by spectrophotometric measurement at 260 and 280 nm. DNA integrity was checked by electrophoresis in 1% agarose gels and ethidium bromide staining. Target cells for transformation were mouse NIH 3T3 cells (CSL Biosciences). The cells were routinely propagated on Minimal Essential Medium (Eagle) supplemented with non-essential amino acids, 2 mM glutamine and 10% foetal bovine serum (growth medium).

Transfection of NIH 3T3 cells with plasmid DNA was carried out essentially as described in the Promega Technical Bulletin No. 216 using Tfx™-50 to enhance DNA uptake. Typical transfection mixtures contained 5 μg of test plasmid (pJ4ΩE6/E7, pJ4ΩE7 or pJ4ΩE6 and pJ4ΩE7), and where required 0.1 μg pcDNA3. Where pJ4ΩE6 and pJ4ΩE7 were cotransfected 2.5 μg of each was used.

Cells were grown to approximately 80% confluency, the growth medium removed and plasmid DNA mixed with Tfx™-50 in a ratio of 4:1 in Minimal Essential Medium was added and the cells incubated at 37° C.

Following 1-2 hours incubation at 37° C. the transfection mixture was removed and fresh growth medium added. After 48 hours incubation at 37° C. transfected cells were removed by trysinization and either assayed for colony formation in soft agar or incubated for a further 24 hours at 37° C. before neomycin selection was applied.

For assay of colony formation in soft agar the trysinized cells were resuspended at a density of 1-5×10⁵ cells/mL in RPMI 1640 supplemented with 10% FBS, 2 mM glutamine, 10 mM Hepes and 0.084% NaHCO₃ (RPMI1640+) and containing 0.4% agarose (Seaplaque low gelling temperature, FMC Bioproducts, USA) maintained at a temperature of 37° C. Following mixing 2.5 mL of this suspension was added to each well of a 6 well tray (Nunc) and allowed to set. The trays were then incubated for a period of 10-14 days at 37° C. in an atmosphere of 5% CO₂, prior to counting of colonies using an inverted light microscope.

Selection of neomycin resistant colonies was carried out on subconfluent cell monolayers using RPMI 1640+ containing 700 μg/mL neomycin (Geneticin). The monolayers were incubated at 37° C. in an atmosphere of 5% CO₂ for 10-14 days prior to counting of neomycin resistant colonies using an inverted light microscope. Following counting, the colonies were dispersed by trysinization and assayed for colony formation in soft agar as described above. The results of a neomycin selection experiment following transfection of 3T3 cells with various plasmid constructs are presented in Table 2.

TABLE 2 Construct No. of neomycin Mean no. of cells (+pcDNA3) resistant colonies per colony pJ4ΩE6/E7 2 10 pJ4ΩE7 4 >65 pJ4ΩE6 + pJ4ΩE7 11 >66

These results indicate that the E6/E7 fusion is only weakly transforming in comparison with E7 or E6+E7. Both colony numbers and cell growth for the E6/E7 fusion were low in comparison with the unfused wild-type sequences. This indicates that the outcome of fusing the E6 and E7 sequences is impairment of the ability of these sequences to promote cell transformation.

EXAMPLE 7

Cloning of HPV-16 E6/HPV-16 E6 Fusion Sequence

A molecule consisting of two copies of HPV-16 E6 as an ‘in frame’ fusion is created as follows.

A clone of HPV-16 DNA containing E6 genomic sequences serves as a template for separate PCR amplification of E6 for the sequence serving as the 5′(N-terminus) portion of the fusion, using the oligonucleotides:

(i) a) (5′)GCGATATCATGCACCAAAAGAGAACTGC(3′) (SEQ ID NO: 16)

b) (5′)CGCCCGGGCAGCTGGGTTTCTCTACGTG(3′) (SEQ ID NO: 17)

and for the E6 sequence serving as the 3′ (C-terminus) portion of the fusion, using the oligonucleotides:

(ii) a) (5′)CGCCCGGGCACCAAAAGAGAACTGCAATG(3′) (SEQ ID NO: 18)

b) (5′)GCAGATCTCAGCTGGGTTTCTCTACGTG(3′) (SEQ ID NO: 19)

These oligonucleotides are designed to facilitate the fusion of two HPV-16 E6 molecules through an XmaI restriction site. An EcoRV site at the 5′ terminus and a Bg/II site at the 3′ terminus are used to assemble the fusion by 3-way ligation in the [GST]ΔE6C/ΔE7Nhh vector (described in Example 3) from which the E6 and E7 sequences are removed by restricting with SmaI and Bg/II.

EXAMPLE 8

Cloning of HPV-16E7/HPV-16E7 Fusion Sequence

A molecule consisting of two copies of HPV-16 E7 as an ‘in frame’ fusion is created as follows.

A clone of HPV-16 DNA containing E7 genomic sequences serves as a template for separate PCR amplification of E7 for the sequence serving as the 5′(N-terminus) portion of the fusion, using the oligonucleotides:

(i) a) (5′)GCGATATCATGCATGGAGATACACCTAC(3′) (SEQ ID NO: 20)

b) (5′)CGCCCGGGTGGTTTCTGAGAACAGATGG(3′) (SEQ ID NO: 21)

and for the E7 sequence serving as the 3′ (C-terminus) portion of the fusion, sing the oligonucleotides:

(ii) a) (5′)CGCCCGGGCATGGAGATACACCTACATT(3′) (SEQ ID NO: 22)

b) (5′)GCAGATCTTGGTTTCTGAGAACAGATGG(SEQ ID NO: 23)

These oligonucleotides are designed to facilitate the fusion of two HPV-16 E7 molecules through an XmaI restriction site. An EcoRV site at the 5′ terminus and a Bg/II site at the 3′ terminus are used to assemble the fusion by 3-way ligation in the [GST]ΔE6C/ΔE7Nhh vector (described in Example 3) from which the E6 and E7 sequences are removed by restricting with SmaI and Bg/II.

EXAMPLE 9

Cloning of HPV-16 E6/HPV-18 E6 Fusion Sequence

A molecule consisting of one copy of HPV-16 E6 and one copy of HPV-18 E6 sequences as an ‘in frame’ fusion is created as follows.

A clone of HPV-16 DNA containing E6 genomic sequences serves as a template for PCR amplification of an E6 sequence, using the oligonucleotides described in Example 7 (i) (a) (SEQ ID NO: 16) and (i) (b) (SEQ ID NO: 17).

A clone of HPV-18 DNA containing E6 genomic sequences serves as template for PCR amplification of an E6 sequence, using the oligonucleotides:

a) (5′)CGCCCGGGGCGCGCTTTGAGGATCCAAC(3′) (SEQ ID NO: 24)

b) (5′)GCAGATCTTACTTGTGTTTCTCTGCGTC(3′) (SEQ ID NO: 25)

These oligonucleotides are designed to facilitate the fusion of two E6 molecules from HPV-16 and HPV-18 respectively, through an XmaI restriction site.

An EcoRV site at the 5′ terminus and a Bg/II site at the 3′ terminus are used to assemble the fusion by 3-way ligation in the [GST]ΔE6C/ΔE7Nhh vector (described in Example 3) from which the E6 and E7 sequences are removed by restricting with SmaI and Bg/II.

EXAMPLE 10

Cloning of HPV-16 E7/HPV-18 E7 Fusion Sequence

A molecule consisting of one copy of HPV-16 E7 and one copy of HPV-18 E7 sequences as an ‘in frame’ fusion is created as follows.

A clone of HPV-16 DNA containing E7 genomic sequences serves as a template for PCR amplification of an E7 sequence, using the oligonucleotides described in Example 8, (i) (a) (SEQ ID NO: 20) and (i) (b) (SEQ ID NO: 21).

A clone of HPV-18 DNA containing E7 genomic sequences serves as template for PCR amplification of an E7 sequence, using the oligonucleotides:

a) (5′)CGCCCGGGCATGGACCTAAGGCAACATT(3′) (SEQ ID NO: 26)

b) (5′)CGAGATCTCTGCTGGGATGCACACCACG(3′) (SEQ ID NO: 27)

These oligonucleotides are designed to facilitate the fusion of two E7 molecules from HPV-16 and HPV-18 respectively, through an XmaI restriction site. An EcoRV site at the 5′ terminus and a Bg/II site at the 3′ terminus are used to assemble the fusion by 3-way ligation in the [GST]ΔE6C/ΔE7Nhh vector (described in Example 3) from which the E6 and E7 sequences are removed by restricting with SmaI and Bg/II.

Persons skilled in this art will appreciate that variations and modifications may be made to the invention as broadly described herein, other than those specifically described without departing from the spirit and scope of the invention. It is to be understood that this invention extends to include all such variations and modifications.

27 1 37 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 1 cgctcgagag atctcatatg caccaaaaga gaactgc 37 2 28 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 2 cgcccgggca gctgggtttc tctacgtg 28 3 36 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 3 cgcccgggat gcatggagat acacctacat tgcatg 36 4 35 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 4 cggtcgacgg atcctggttt ctgagaacag atggg 35 5 48 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 5 gcgcgaattc tattaaggag cccgggatgg ggaatccata tgctgtat 48 6 32 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 6 cgcgagatct ccgaagcgta gagtcacact tg 32 7 30 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 7 cgcccgggta atgttgttcc atacaaacta 30 8 30 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 8 cgcccgggga ggaggaggat gaaatagatg 30 9 801 DNA Human papillomavirus type 16 CDS (1)..(798) 9 atg cac caa aag aga act gca atg ttt cag gac cca cag gag cga ccc 48 Met His Gln Lys Arg Thr Ala Met Phe Gln Asp Pro Gln Glu Arg Pro 1 5 10 15 aga aag tta cca cag tta tgc aca gag ctg caa aca act ata cat gat 96 Arg Lys Leu Pro Gln Leu Cys Thr Glu Leu Gln Thr Thr Ile His Asp 20 25 30 ata ata tta gaa tgt gtg tac tgc aag caa cag tta ctg cga cgt gag 144 Ile Ile Leu Glu Cys Val Tyr Cys Lys Gln Gln Leu Leu Arg Arg Glu 35 40 45 gta tat gac ttt gct ttt cgg gat tta tgc ata gta tat aga gat ggg 192 Val Tyr Asp Phe Ala Phe Arg Asp Leu Cys Ile Val Tyr Arg Asp Gly 50 55 60 aat cca tat gct gta tgt gat aaa tgt tta aag ttt tat tct aaa att 240 Asn Pro Tyr Ala Val Cys Asp Lys Cys Leu Lys Phe Tyr Ser Lys Ile 65 70 75 80 agt gag tat aga cat tat tgt tat agt ttg tat gga aca aca tta gaa 288 Ser Glu Tyr Arg His Tyr Cys Tyr Ser Leu Tyr Gly Thr Thr Leu Glu 85 90 95 cag caa tac aac aaa ccg ttg tgt gat ttg tta att agg tgt att aac 336 Gln Gln Tyr Asn Lys Pro Leu Cys Asp Leu Leu Ile Arg Cys Ile Asn 100 105 110 tgt caa aag cca ctg tgt cct gaa gaa aag caa aga cat ctg gac aaa 384 Cys Gln Lys Pro Leu Cys Pro Glu Glu Lys Gln Arg His Leu Asp Lys 115 120 125 aag caa aga ttc cat aat ata agg ggt cgg tgg acc ggt cga tgt atg 432 Lys Gln Arg Phe His Asn Ile Arg Gly Arg Trp Thr Gly Arg Cys Met 130 135 140 tct tgt tgc aga tca tca aga aca cgt aga gaa acc cag ctg ccc ggg 480 Ser Cys Cys Arg Ser Ser Arg Thr Arg Arg Glu Thr Gln Leu Pro Gly 145 150 155 160 atg cat gga gat aca cct aca ttg cat gaa tat atg tta gat ttg caa 528 Met His Gly Asp Thr Pro Thr Leu His Glu Tyr Met Leu Asp Leu Gln 165 170 175 cca gag aca act gat ctc tac tgt tat gag caa tta aat gac agc tca 576 Pro Glu Thr Thr Asp Leu Tyr Cys Tyr Glu Gln Leu Asn Asp Ser Ser 180 185 190 gag gag gag gat gaa ata gat ggt cca gct gga caa gca gaa ccg gac 624 Glu Glu Glu Asp Glu Ile Asp Gly Pro Ala Gly Gln Ala Glu Pro Asp 195 200 205 aga gcc cat tac aat att gta acc ttt tgt tgc aag tgt gac tct acg 672 Arg Ala His Tyr Asn Ile Val Thr Phe Cys Cys Lys Cys Asp Ser Thr 210 215 220 ctt cgg ttg tgc gta caa agc aca cac gta gac att cgt act ttg gaa 720 Leu Arg Leu Cys Val Gln Ser Thr His Val Asp Ile Arg Thr Leu Glu 225 230 235 240 gac ctg tta atg ggc aca cta gga att gtg tgc ccc atc tgt tct cag 768 Asp Leu Leu Met Gly Thr Leu Gly Ile Val Cys Pro Ile Cys Ser Gln 245 250 255 aaa cca aga tct cat cac cat cac cat cac taa 801 Lys Pro Arg Ser His His His His His His 260 265 10 266 PRT Human papillomavirus type 16 10 Met His Gln Lys Arg Thr Ala Met Phe Gln Asp Pro Gln Glu Arg Pro 1 5 10 15 Arg Lys Leu Pro Gln Leu Cys Thr Glu Leu Gln Thr Thr Ile His Asp 20 25 30 Ile Ile Leu Glu Cys Val Tyr Cys Lys Gln Gln Leu Leu Arg Arg Glu 35 40 45 Val Tyr Asp Phe Ala Phe Arg Asp Leu Cys Ile Val Tyr Arg Asp Gly 50 55 60 Asn Pro Tyr Ala Val Cys Asp Lys Cys Leu Lys Phe Tyr Ser Lys Ile 65 70 75 80 Ser Glu Tyr Arg His Tyr Cys Tyr Ser Leu Tyr Gly Thr Thr Leu Glu 85 90 95 Gln Gln Tyr Asn Lys Pro Leu Cys Asp Leu Leu Ile Arg Cys Ile Asn 100 105 110 Cys Gln Lys Pro Leu Cys Pro Glu Glu Lys Gln Arg His Leu Asp Lys 115 120 125 Lys Gln Arg Phe His Asn Ile Arg Gly Arg Trp Thr Gly Arg Cys Met 130 135 140 Ser Cys Cys Arg Ser Ser Arg Thr Arg Arg Glu Thr Gln Leu Pro Gly 145 150 155 160 Met His Gly Asp Thr Pro Thr Leu His Glu Tyr Met Leu Asp Leu Gln 165 170 175 Pro Glu Thr Thr Asp Leu Tyr Cys Tyr Glu Gln Leu Asn Asp Ser Ser 180 185 190 Glu Glu Glu Asp Glu Ile Asp Gly Pro Ala Gly Gln Ala Glu Pro Asp 195 200 205 Arg Ala His Tyr Asn Ile Val Thr Phe Cys Cys Lys Cys Asp Ser Thr 210 215 220 Leu Arg Leu Cys Val Gln Ser Thr His Val Asp Ile Arg Thr Leu Glu 225 230 235 240 Asp Leu Leu Met Gly Thr Leu Gly Ile Val Cys Pro Ile Cys Ser Gln 245 250 255 Lys Pro Arg Ser His His His His His His 260 265 11 519 DNA Human papillomavirus type 16 CDS (1)..(516) 11 atg ggg aat cca tat gct gta tgt gat aaa tgt tta aag ttt tat tct 48 Met Gly Asn Pro Tyr Ala Val Cys Asp Lys Cys Leu Lys Phe Tyr Ser 1 5 10 15 aaa att agt gag tat aga cat tat tgt tat agt ttg tat gga aca aca 96 Lys Ile Ser Glu Tyr Arg His Tyr Cys Tyr Ser Leu Tyr Gly Thr Thr 20 25 30 tta gaa cag caa tac aac aaa ccg ttg tgt gat ttg tta att agg tgt 144 Leu Glu Gln Gln Tyr Asn Lys Pro Leu Cys Asp Leu Leu Ile Arg Cys 35 40 45 att aac tgt caa aag cca ctg tgt cct gaa gaa aag caa aga cat ctg 192 Ile Asn Cys Gln Lys Pro Leu Cys Pro Glu Glu Lys Gln Arg His Leu 50 55 60 gac aaa aag caa aga ttc cat aat ata agg ggt cgg tgg acc ggt cga 240 Asp Lys Lys Gln Arg Phe His Asn Ile Arg Gly Arg Trp Thr Gly Arg 65 70 75 80 tgt atg tct tgt tgc aga tca tca aga aca cgt aga gaa acc cag ctg 288 Cys Met Ser Cys Cys Arg Ser Ser Arg Thr Arg Arg Glu Thr Gln Leu 85 90 95 ccc ggg atg cat gga gat aca cct aca ttg cat gaa tat atg tta gat 336 Pro Gly Met His Gly Asp Thr Pro Thr Leu His Glu Tyr Met Leu Asp 100 105 110 ttg caa cca gag aca act gat ctc tac tgt tat gag caa tta aat gac 384 Leu Gln Pro Glu Thr Thr Asp Leu Tyr Cys Tyr Glu Gln Leu Asn Asp 115 120 125 agc tca gag gag gag gat gaa ata gat ggt cca gct gga caa gca gaa 432 Ser Ser Glu Glu Glu Asp Glu Ile Asp Gly Pro Ala Gly Gln Ala Glu 130 135 140 ccg gac aga gcc cat tac aat att gta acc ttt tgt tgc aag tgt gac 480 Pro Asp Arg Ala His Tyr Asn Ile Val Thr Phe Cys Cys Lys Cys Asp 145 150 155 160 tct acg ctt cgg aga tct cat cac cat cac cat cac taa 519 Ser Thr Leu Arg Arg Ser His His His His His His 165 170 12 172 PRT Human papillomavirus type 16 12 Met Gly Asn Pro Tyr Ala Val Cys Asp Lys Cys Leu Lys Phe Tyr Ser 1 5 10 15 Lys Ile Ser Glu Tyr Arg His Tyr Cys Tyr Ser Leu Tyr Gly Thr Thr 20 25 30 Leu Glu Gln Gln Tyr Asn Lys Pro Leu Cys Asp Leu Leu Ile Arg Cys 35 40 45 Ile Asn Cys Gln Lys Pro Leu Cys Pro Glu Glu Lys Gln Arg His Leu 50 55 60 Asp Lys Lys Gln Arg Phe His Asn Ile Arg Gly Arg Trp Thr Gly Arg 65 70 75 80 Cys Met Ser Cys Cys Arg Ser Ser Arg Thr Arg Arg Glu Thr Gln Leu 85 90 95 Pro Gly Met His Gly Asp Thr Pro Thr Leu His Glu Tyr Met Leu Asp 100 105 110 Leu Gln Pro Glu Thr Thr Asp Leu Tyr Cys Tyr Glu Gln Leu Asn Asp 115 120 125 Ser Ser Glu Glu Glu Asp Glu Ile Asp Gly Pro Ala Gly Gln Ala Glu 130 135 140 Pro Asp Arg Ala His Tyr Asn Ile Val Thr Phe Cys Cys Lys Cys Asp 145 150 155 160 Ser Thr Leu Arg Arg Ser His His His His His His 165 170 13 519 DNA Human papillomavirus type 16 CDS (1)..(516) 13 atg gag gag gat gaa ata gat ggt cca gct gga caa gca gaa ccg gac 48 Met Glu Glu Asp Glu Ile Asp Gly Pro Ala Gly Gln Ala Glu Pro Asp 1 5 10 15 aga gcc cat tac aat att gta acc ttt tgt tgc aag tgt gac tct acg 96 Arg Ala His Tyr Asn Ile Val Thr Phe Cys Cys Lys Cys Asp Ser Thr 20 25 30 ctt cgg ttg tgc gta caa agc aca cac gta gac att cgt act ttg gaa 144 Leu Arg Leu Cys Val Gln Ser Thr His Val Asp Ile Arg Thr Leu Glu 35 40 45 gac ctg tta atg ggc aca cta gga att gtg tgc ccc atc tgt tct cag 192 Asp Leu Leu Met Gly Thr Leu Gly Ile Val Cys Pro Ile Cys Ser Gln 50 55 60 aaa cca gga tct cat atg cac caa aag aga act gca atg ttt cag gac 240 Lys Pro Gly Ser His Met His Gln Lys Arg Thr Ala Met Phe Gln Asp 65 70 75 80 cca cag gag cga ccc aga aag tta cca cag tta tgc aca gag ctg caa 288 Pro Gln Glu Arg Pro Arg Lys Leu Pro Gln Leu Cys Thr Glu Leu Gln 85 90 95 aca act ata cat gat ata ata tta gaa tgt gtg tac tgc aag caa cag 336 Thr Thr Ile His Asp Ile Ile Leu Glu Cys Val Tyr Cys Lys Gln Gln 100 105 110 tta ctg cga cgt gag gta tat gac ttt gct ttt cgg gat tta tgc ata 384 Leu Leu Arg Arg Glu Val Tyr Asp Phe Ala Phe Arg Asp Leu Cys Ile 115 120 125 gta tat aga gat ggg aat cca tat gct gta tgt gat aaa tgt tta aag 432 Val Tyr Arg Asp Gly Asn Pro Tyr Ala Val Cys Asp Lys Cys Leu Lys 130 135 140 ttt tat tct aaa att agt gag tat aga cat tat tgt tat agt ttg tat 480 Phe Tyr Ser Lys Ile Ser Glu Tyr Arg His Tyr Cys Tyr Ser Leu Tyr 145 150 155 160 gga aca aca tta aga tct cat cac cat cac cat cac taa 519 Gly Thr Thr Leu Arg Ser His His His His His His 165 170 14 172 PRT Human papillomavirus type 16 14 Met Glu Glu Asp Glu Ile Asp Gly Pro Ala Gly Gln Ala Glu Pro Asp 1 5 10 15 Arg Ala His Tyr Asn Ile Val Thr Phe Cys Cys Lys Cys Asp Ser Thr 20 25 30 Leu Arg Leu Cys Val Gln Ser Thr His Val Asp Ile Arg Thr Leu Glu 35 40 45 Asp Leu Leu Met Gly Thr Leu Gly Ile Val Cys Pro Ile Cys Ser Gln 50 55 60 Lys Pro Gly Ser His Met His Gln Lys Arg Thr Ala Met Phe Gln Asp 65 70 75 80 Pro Gln Glu Arg Pro Arg Lys Leu Pro Gln Leu Cys Thr Glu Leu Gln 85 90 95 Thr Thr Ile His Asp Ile Ile Leu Glu Cys Val Tyr Cys Lys Gln Gln 100 105 110 Leu Leu Arg Arg Glu Val Tyr Asp Phe Ala Phe Arg Asp Leu Cys Ile 115 120 125 Val Tyr Arg Asp Gly Asn Pro Tyr Ala Val Cys Asp Lys Cys Leu Lys 130 135 140 Phe Tyr Ser Lys Ile Ser Glu Tyr Arg His Tyr Cys Tyr Ser Leu Tyr 145 150 155 160 Gly Thr Thr Leu Arg Ser His His His His His His 165 170 15 12 DNA Artificial Sequence Description of Artificial Sequence Phosphorylated linker 15 tgctctagag ca 12 16 28 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 16 gcgatatcat gcaccaaaag agaactgc 28 17 28 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 17 cgcccgggca gctgggtttc tctacgtg 28 18 29 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 18 cgcccgggca ccaaaagaga actgcaatg 29 19 28 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 19 gcagatctca gctgggtttc tctacgtg 28 20 28 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 20 gcgatatcat gcatggagat acacctac 28 21 28 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 21 cgcccgggtg gtttctgaga acagatgg 28 22 28 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 22 cgcccgggca tggagataca cctacatt 28 23 28 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 23 gcagatcttg gtttctgaga acagatgg 28 24 28 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 24 cgcccggggc gcgctttgag gatccaac 28 25 28 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 25 gcagatctta cttgtgtttc tctgcgtc 28 26 28 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 26 cgcccgggca tggacctaag gcaacatt 28 27 28 DNA Artificial Sequence Description of Artificial Sequence Oligonucleotide used for PCR amplification 27 cgagatctct gctgggatgc acaccacg 28 

What is claim is:
 1. An isolated variant human papillomavirus (HPV) protein able to elicit an immune response against HPV in a host animal but not being cell-transforming in said host animal, wherein said variant protein comprises a fusion protein comprising a first HPV E6 protein selected from the group consisting of full length E6 protein and non-full length deletion mutants thereof, and a second HPV E6 protein selected from the group consisting of full length E6 protein and non-full length deletion mutants thereof, and optionally a linker linking said first and second proteins.
 2. An isolated variant human papillomavirus (HPV) protein able to elicit an immune response against HPV in a host animal but not being cell-transforming in said host animal, wherein said variant protein comprises a fusion protein comprising a first HPV E7 protein selected from the group consisting of full length E7 protein and non-full length deletion mutants thereof, and a second HPV E7 protein selected from the group consisting of full length E7 protein and non-full length deletion mutants thereof, and optionally a linker linking said first and second proteins.
 3. An isolated variant HPV protein according to claim 1, wherein said first and second proteins are selected from different HPV genotypes.
 4. An isolated variant HPV protein according to claim 1, wherein said protein further comprises a foreign protein or peptide fused or otherwise coupled to one or both of said first and second proteins.
 5. An isolated variant HPV protein according to claim 4, wherein the foreign protein or peptide is selected from the group consisting of (i) proteins or peptides to assist in purification of the fusion protein or (ii) proteins or peptides to enhance the immunogenicity of the fusion protein.
 6. An isolated variant HPV protein according to claim 1, which comprises a fusion protein comprising a first full length E6 protein fused to a second full length E6 protein.
 7. An isolated variant HPV protein according to claim 2, which comprises a fusion protein comprising a first full length E7 protein fused to a second full length E7 protein.
 8. An isolated variant HPV protein according to claim 1, comprising a first non-full length deletion mutant of the E6 protein fused to a second non-full length deletion mutant of the E6 protein.
 9. An isolated variant HPV protein according to claim 2, comprising a first non-full length deletion mutant of the E7 protein fused to a second non-full length deletion mutant of the E7 protein.
 10. An isolated variant HPV protein according to claim 1, wherein each deletion mutant of the E6 or E7 protein comprises at least 50% of the full length sequence of the protein.
 11. An isolated variant HPV protein according to claim 10, wherein each deletion mutant of the E6 or E7 protein comprises at least 60% of the full length sequence of the protein.
 12. An isolated variant HPV protein according to claim 11, wherein each deletion mutant of the E6 or E7 protein comprises at least the N-terminal 60% of the full length sequence of the protein.
 13. An isolated variant HPV protein according to claim 11, wherein each deletion mutant of the E6 or E7 protein comprises at least the C-terminal 60% of the full length sequence of the protein.
 14. An isolated variant HPV protein according to claim 1, wherein said linker consists of from 1 to 50 amino acid residues.
 15. An isolated variant HPV protein according to claim 14, wherein said linker consists of from 1 to 20 amino acid residues.
 16. An isolated variant HPV protein according to claim 15, wherein said linker consists of from 1 to 5 amino acid residues.
 17. An isolated variant HPV protein according to claim 1, wherein said first and second HPV proteins are selected from the group consisting of HPV-16, HPV-18, HPV-6 and HPV-11 genotypes.
 18. An isolated variant HPV protein according to claim 17, wherein said first and second HPV proteins are selected from the group consisting of HPV-16 and HPV-18 genotypes.
 19. A composition for use in eliciting an immune response against HPV in a host animal, said composition comprising an isolated variant HPV protein according to claim 1, together with a pharmaceutically acceptable carrier and/or diluent.
 20. A composition according to claim 19, further comprising an adjuvant.
 21. A method for eliciting an immune response against HPV in a host animal, which method comprises administering to the host animal an effective amount of an isolated variant HPV protein according to claim
 1. 22. A method according to claim 21, wherein said variant HPV protein is administered in a composition together with a pharmaceutically acceptable carrier and/or diluent.
 23. A method according to claim 22, wherein said composition further comprises an adjuvant.
 24. A method according to claim 21, wherein said host animal is a human.
 25. An isolated variant HPV protein according to claim 2, wherein said first and second proteins are selected from different HPV genotypes.
 26. An isolated variant HPV protein according to claim 2, wherein said protein further comprises a foreign protein or peptide fused or otherwise coupled to one or both of said first and second proteins.
 27. An isolated variant HPV protein according to claim 3, wherein said protein further comprises a foreign protein or peptide fused or otherwise coupled to one or both of said first and second proteins.
 28. An isolated variant HPV protein according to claim 2, wherein each deletion mutant of the E6 or E7 protein comprises at least 50% of the full length sequence of the protein.
 29. An isolated variant HPV protein according to claim 2, wherein said linker consists of from 1 to 50 amino acid residues.
 30. An isolated variant HPV protein according to claim 2, wherein said first and second HPV proteins are selected from the group consisting of HPV-16, HPV-18, HPV-6 and HPV-11 genotypes.
 31. A composition for use in eliciting an immune response against HPV in a host animal, said composition comprising an isolated variant HPV protein according to claim 2, together with a pharmaceutically acceptable carrier and/or diluent.
 32. A method for eliciting an immune response against HPV in a host animal, which method comprises administering to the host animal an effective amount of an isolated variant HPV protein according to claim
 2. 33. An isolated variant human papillomavirus (HPV) protein able to elicit an immune response against HPV in a host animal but not being cell-transforming in said host animal, wherein said variant protein is either: (a) a fusion protein comprising a first HPV E6 protein selected from the group consisting of full length E6 protein and non-full length deletion mutants thereof, and a second HPV E6 protein selected from the group consisting of full length E6 protein and non-full length deletion mutants thereof, and optionally a linker linking said first and second HPV E6 proteins, or (b) a fusion protein comprising a first HPV E7 protein selected from the group consisting of full length E7 protein and non-full length deletion mutants thereof, and a second HPV E7 protein selected from the group consisting of full length E7 protein and non-full length deletion mutants thereof, and optionally a linker linking said first and second HPV E7 proteins. 